proceedings: botanical society 87 



resistance is dominant. In the second generation about one-third of 

 the plants were sterile, the percentage being as high as 73 in some 

 hybrids. About 67 per cent of the plants were seed producing. 



In the case of the watermelon, the citron or stock melon was used in 

 breeding for a disease-resistant variety. In the first generation in- 

 creased vigor was very noticeable, and in the second generation char- 

 acters were noted Which had not been noted before in either of the 

 parents, particularly in the colors of the fruits, and also in a bitter 

 taste not noted in either of the parents. 



Mr. W. J. Morse called attention to the behavior of hybrids in the 

 soy bean, in which group study was made of the following characters: 

 (1) flowers (white, purple); (2) pubescence (white, tawny); (3) seed 

 (yellow, green, brown, black, bicolored); (4) cotyledons (yellow, green); 

 (5) hypocotyl (green, purple); (6) smoothness; and (7) non-shattering. 

 All of these are found to behave as Mendelian characters and to segre- 

 gate according to Mendelian ratio. The only interrelation of characters 

 noted is between the flower and the hypocotyl, the white flower being 

 associated with the green hypocot}*! and the purple flower with the 

 purple hypocotyl. The non-shattering character is held to be one of 

 the most important, and hybrids with this character have been fixed. 

 Further work on this character with the standard commercial varieties 

 is in progress. In the course of the hybrid work numerous sterile 

 plants have been found. Natural hybrids of F x generation can usually 

 be told in the field by the plants having a few smooth pods at the tip 

 of the branches. 



With the cowpea a large number of crosses have been made between 

 the different commercial sorts, seeking to combine desirable characters. 

 A stud}* of the seed colors shows them to segregate in Mendelian ratio. 

 Wilt and nematode resistance have been fixed in hybrids. 



In the case of alfalfa, when hybrids of tender forms of Medicago 

 sativa, such as Peruvian alfalfa, are made with Medicago falcata and the 

 offspring subjected to severe winter conditions, there appears to be no 

 tendency toward the elimination of the. blue or purple-flowered forms, 

 indicating that flower color is not particularly correlated with char- 

 acters resulting in hardiness. There have been several crosses reported 

 between rather distantly related species of Medicago, but it is believed 

 that most of them are not true hybrids. It is believed that the Medicago 

 sativa X prostrata hybrid is the only authentic one in the genus Medi- 

 cago dutside of the forms which Urban lists in his classification under 

 Medicago sativa, which include Medicago falcata and M . glandidosa. 



Mr. Walter T. Swingle called attention to the great difference in 

 the behavior of Citrus from other groups mentioned, in that a larger 

 amount of variability occurred in the first generation of the hybrids. 

 In Citrus many of these first generation hybrids are of commercial 

 value and may be propagated without variation from seeds which con- 

 tain usually only false embryos originating from the nucellar tissue of 

 the mother plant. For example, hybrids secured between Poncirus 

 trifoliata and the common orange, Citrus sinensis, are sterile, notwith- 



